1. Field
The present invention relates to a lithographic apparatus and a method for manufacturing a device.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs), micro-electro-mechanical-systems (MEMS), and other devices involving fine structures. In a conventional apparatus, a contrast device or a patterning device, which can be referred to as a mask or a reticle, can be used to generate a circuit pattern corresponding to an individual layer of a flat panel display or other device. This pattern can be transferred onto a target portion (e.g., comprising part of one or several dies) on a substrate (e.g., a glass plate). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (e.g., resist) provided on the substrate.
Instead of a circuit pattern, the patterning device can be used to generate other patterns, for example a color filter pattern or a matrix of dots. Instead of a mask, the patterning device can comprise a patterning array that comprises an array of individually controllable elements. An advantage of such a system compared to a mask-based system is that the pattern can be changed more quickly and for less cost.
In general, a flat panel display substrate is rectangular in shape. Known lithographic apparatus designed to expose a substrate of this type typically provide an exposure region, which covers a full width of the rectangular substrate, or which covers a portion of the width (e.g., about half of the width). The substrate is scanned underneath the exposure region, while the mask or reticle is synchronously scanned through the beam. In this way, the pattern is transferred to the substrate. If the exposure region covers the full width of the substrate, then exposure is completed with a single scan. If the exposure region covers, for example, half of the width of the substrate, then the substrate is moved transversely after the first scan, and a second scan is performed to expose the remainder of the substrate.
Another way of imaging includes pixel grid imaging, in which a pattern is realized by successive exposure of spots.
The individually controllable elements can be controlled in one of two ways: (1) by controlling the tilt of the individually controllable element or (2) by controlling the position (in a direction perpendicular to the plane of the individually controllable elements) of the individually controllable elements. The tilt of the individually controllable element can be used to deflect a portion of the radiation beam either towards the substrate or away from the substrate. The position of the individually controllable element can be used to change the path length of a portion of the radiation beam and create destructive interference. Each of these methods has different advantages. For example, adjusting the position of the mirrors allows for imparting any phase to the reflected beam and thus allows emulation of any type of mask (e.g., binary masks, attenuated phase shift masks, masks with any phase e.g. vortex masks, etc.), while adjusting the tilt yields a reflected intensity either in phase or (with a certain limited amplitude) of exactly opposite phase to the incoming beam.
Therefore, what is needed is a system and method that using the beneficial effect of adjusting both the tilt and position of an individually controllable element.